The manipulation of hypodermic syringes, particularly of those already used, entails a risk, bearing in mind the nature thereof and their condition of sharpened elements, which are susceptible of easily penetrating or injuring animal tissues.
Therefore, in manipulating said instruments, physicians and nurses, to reduce the risk of injuring themselves or contaminating the needles, try to withdraw the hood or protecting sheath only at the moment of use. Said protecting sheath is a lengthened receptacle into which said needle is introduced through one of the open ends of the sheath, which is normally, closed at the other end.
Although the sheath offers acceptable safety during manipulation of the needle until its use on the patient, the sheath does not give any safety after the moment in which it is withdrawn, because the sheath has a very small diameter. It is very easy to fail in the attempt of re-inserting the needle in the sheath and the needle may injure the person effecting the maneuver, with the imaginable risk of disease transmissions, since the needle has been already used and is already contaminated.
For this reason, it is now recommended to avoid making the re-sheathing maneuver, and it is insisted that a rigid and strong casing be used as a receptacle for contaminated needles.
However, in many cases, the assembly of needle and syringe cannot be discarded inside said casing, either because the casing is not at hand, or because it is imperative to extract the needle from the syringe. For example, in blood extractions, for passing the blood to the test tubes, the needle should not be maintained inserted, as the passage of blood from the syringe through the needle produces hemolysis, i.e., destruction of the red cells, with the consequence that the blood sample is unusable.
It is in this moment when the maneuver required to withdraw the needle offers the above cited dangers of contagion by wounds or contamination by contact with the blood.
In order to avoid such risks, several apparatuses have been conceived for separating the needle from the syringe. The U.S. Pat. No. 4,375,849, of Sage Products, Inc., granted Mar. 8, 1983, protects an apparatus of cylindrical configuration which has in an end a key-shaped orifice, with the opposite end being closed. For the operation of said apparatus, the cylinder is taken with one hand and, with the opposed hand, the syringe with the mounted needle is taken, and the needle is introduced in the widest portion of the orifice. Then the needle is run to the narrowest portion of said orifice with the purpose of locking the base of the needle. When pulling, the needle is dislodged and the needle is definitely housed inside the cylinder. The operation of this apparatus brings out the risk of opposing the point of the contaminated needle to the hand holding the apparatus, since in if attempting to introduce the needle in the orifice such attempt fails, it is very possible that the hand holding the apparatus will be injured.
Argentine Pat. No. 239,895, granted to Susana Giron and Hugo Di Placido, on Dec. 29, 1989, protects a device that, as expressed in the description of the invention, "is apt for being located in the access mouthpiece of the residue containers which are used for this type of refuse, in Clinics, Sanatoriums and Hospitals, and consists of a lock", which comprises "an access orifice having its upper part of a larger diameter than the lower one". That is, the needle should be introduced by its point in the larger diameter portion of the orifice and then it should be inserted in the lower portion thereof, and once inserted, the syringe is pulled and then steps are taken to dislodge the needle.
This device is to be located in fixed places and it is not portable, for which reason it is possible that it is not found in the place where it should be used. Then the personnel should have to move for a distance of several metres upto where the device is located, with the risks implied by this fact.
U.S. Pat. No. 4,576,281, owned by University Hospital, granted on Mar. 18, 1986, relates to an apparatus which is stationary, with an orifice in its upper face. Said orifice consists also of a larger diameter portion and another of a lesser diameter, in order to introduce the needle by its point in the wide portion of the cited orifice and then to introduce it in the narrower portion. Then one proceeds to pull the syringe and unlock the needle, which falls in a container. This device is not portable and brings about the same drawbacks of the previous case.
U.S. Pat. No. 4,351,434, owned by Benjamin Elisha, granted on Sept. 28, 1982, protects a device with a container for receiving and holding hypodermic needles. The container has an opening through which a discardable needle having a needle stem and a fitting portion can be passed, while it is mounted in a syringe but which, by withdrawal of the latter, locks the fitting portion of the needle for withdrawing the latter from the syringe.
This device, as that of the U.S. Pat. No. 4,375,849, has the serious drawback that its use has the risk of opposing the point of the needle, which is to be withdrawn, to the hand holding the apparatus, with the very probable chance of wounding said hand in the case of failing in the attempt of introducing the needle through the opening of the device.
Within the state of the art, U.S. Pat. Nos. 4,793,587, granted to Willoughby G. M., and 4,738,362 granted to Beral Enterprises may be cited.